Luminaires have a well-documented history of providing illumination in dark environments. Due to the high market demand for luminaries in all settings, innovation and improvements continue. One common application is in commercial and industrial settings. Such areas typically use volumetric luminaries adapted for recessed mounting in a suspended ceiling, that is, a portion of the troffer protrudes into the ceiling. Recessed ceilings are those which contain a hollow opening, known as the plenum area, for receiving components such as electrical wiring and light fixtures. These ceilings typically have support members, such as T bars, on which the square or rectangular ceiling tiles or lighting fixtures are placed. Recessed lights, such as troffers, fit within the plenum such that light shines onto an environment in a downward direction.
Traditional troffer-type fixtures were originally designed for fluorescent lamps. U.S. Pat. No. 5,823,663 to Bell et al. describes a fluorescent troffer lighting fixture intended for recessed mounting. These luminaires were visually appealing in that their texture and patterns were dynamic and interesting. However, these lamps have the drawback of high energy consumption, resulting in increased costs, and heat production, causing an increase in ambient temperature as well as a decrease in the life of the fixture. To solve these issues, light emitting diodes (LEDs) have emerged as an alternative. LEDs consume relatively low power and last much longer than conventional lamps. LEDs can be dimmed or cycled on and of without any significant adverse effect on its performance or lifetime. Additionally, LEDs emit a radiance more akin to that of natural daylight, lending for better aesthetics in the area being lit.
While these volumetric luminaries have replaced the fluorescent lamps with LEDs, they have not been redesigned to change the mechanical size. U.S. Pat. No. 8,905,575 to Durkee et al. and U.S. Pat. No. 9,494,293 to Pickard disclose troffer-style lighting fixtures adapted to include LEDs. A drawback of these fixtures is the extra volume and weight associated with the deep mixing chamber necessary to properly emit light. These deep optical chambers have corners and areas where light is not reflected well, resulting in uneven lighting and shadows. Some areas experience over-brightness, causing visual discomfort to users. Indeed, these deep mixing chambers cause the luminaire to extend up to four to six inches into the plenum area above the ceiling. This plenum area is often crowded with wiring and electrical components. Moreover, modern buildings are reducing ceiling space rendering these fixtures structurally too bulky.
To eliminate these size and weight concerns, edge-lit flat panels have emerged as a light source. Various forms of this technology have been introduced in applications such as signs, flat screen televisions, laptops, mobile phones, luminaries, and other displays. While these panels present an evenly lit surface, the flat surface causes the light to be emitted in a Lambertian distribution, resulting in uncomfortable glare. Another problem with edge-lit panels is they often entail the assembly of multiple separate components. For instance, U.S. patent application Ser. No. 13/473,929 teaches a flat panel lighting device. This arrangement greatly complicates the manufacturing process, thereby resulting in increased costs. Further, these large panels lack visual interest as they typically appear as a single square or rectangular slab when viewed in the ceiling. Thus, there is a need for visually appealing yet space-efficient lighting in commercial settings.